1.2 Functional anatomy Flashcards
What can the nervous system be split up into?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What is the CNS made up of?
Brain and spinal cord
- two components are seamlessly interconnected and comprise a functional unit
What is the PNS comprised of?
Cranial nerves - connecting to the brain
Spinal nerves - connecting to the spinal cord
What is the afferent system?
Sensory
- nerves that transmit impulses towards the brain and SC
What is the efferent system?
Motor
- nerves that transmit impulses away from the brain and SC
Describe the flow of information through the CNS
Afferent → CNS →Efferent
What is the somatic nervous system?
Somatic (voluntary)
- coordinated voluntary activities such as movement
What is the visceral nervous system?
Visceral (vegetative)
- responsible for involuntary activity such as modulation of cardiac function and digestion
What are the three components of a neuron?
- Cell body (soma): from which fundamentally two different processes arise
- Dendrites: also called receptor segment-conduct impulses to the cell body
- Axon or neuron fibre: also called the projecting segment: relays impulses to other neurons. Each neuron has only one axon.
What is the dorsal root ganglia?
Made up of aggregations, of the soma, of the afferent or sensory neurons
What are pseudounipolar neurones?
Dendrites and axon not separated by cell body
What are bipolar neurones?
Dendrites arborizes in the periphery
What are multipolar neurons?
Multiple dendrites with long axon
What are neuroglia?
Cells that surround the neurons providing them with structural and functional support and absorb excess neurotransmitter
What are neuroglia involved in?
- Absorbing excess neurotransmitter
- Maintaining the structure of the organ
- provide a means through which nourishment of the brain/nervous system is achieved
Why are neuroglia associated with brain tumours?
Capable of mitotic activity
- do not conduct signals
What is the role of astrocytes?
Support + nutrition + structure
What are the functions of oligodendrocytes?
Equivalent of Schwann cells in the peripheral NS = insulate axons in the brain and prevent leakage of ions
What is the function of microglia cells?
Important in the removal of necrotic material
What cells myelinate axons in the PNS and CNS
PNS = Schwann cells CNS = oligodendrocytes
What effect does myelination have on nerve conduction velocity?
Increases due to saltatory effect
What is the significance of myelination in Multiple Sclerosis?
Oligodendrocytes are destroyed whilst Schwann cells are not
What is grey matter?
Nerve cell bodies - appear grey due to the presence of nuclei
What is white matter?
Nerve cell processes and their insulating myelin sheath
What is a synapse?
Functional connections between two neurons or between a neuron and an effector organ
How is the brain supplied with blood?
Carotid arteries - internal supply blood to brain
- also included are the vertebral artery and Basilar artery
Where does blood pool in all species?
Cerebral arterial circle (Circle of Willis) before distribution to the brain
What is the ventricular system?
System of cavities (ventricles) with the CNS
- has ependymal (epithelial cells) that secrete cerebrospinal fluid from choroid plexus
What is an abnormal accumulation of CSF?
Hydrocephalus
How is the CNS protected from injury?
Cranium - lined by the Dura Mater
Vertebrae (spinal cord)
Between bony casing and the CNS are meninges (membranes) which provide further protection
